Reflexed flowers in Aeschynomene amorphoides (Fabaceae: Faboideae): A mechanism promoting pollination specialization?

Abstract

This study aims to understand the role of floral traits in determining the reproductive biology of the leguminous shrub Aeschynomene amorphoides, endemic to western Mexico, which has unusually orientated flowers. We investigated the floral biology, pollination and breeding system based on a combination of morphological studies and field experiments, using controlled pollinations in a natural environment. The architecture and reflexed position of A.amorphoides flowers facilitate precise placement of pollen on the body of the pollinator, but this has a cost to A.amorphoides in terms of available flower resources. These costs to reproduction success are set against the attraction of a specialized pollinator, Tetraloniella jaliscoensis, which is capable of manipulating this unique pollination system in papilionoid (or flag) flowers.